Image inspection method and sound inspection method

Abstract

An image inspection method may include sampling a continuous digital image signal by dividing the signal by less than or equal to 20 msec; extracting a high-frequency component from the sampled signal; and detecting an error occurred in an image on the basis of the extracted high-frequency component.

1 . An image inspection method comprising:
 sampling a continuous digital image signal by dividing the signal by less than or equal to 20 msec;   extracting a high-frequency component from the sampled signal; and   detecting an error occurred in an image on the basis of the extracted high-frequency component.   
     
     
         2 . The image inspection method according to  claim 1 , further comprising dividing one frame of the digital image signal into a plurality of areas, and detecting the error for each of the areas. 
     
     
         3 . The image inspection method according to  claim 1 ,
 wherein the error is an image disorder, and the extracted high-frequency component is an activity, the activity being an average of the variances of the digital image signal for each block.   
     
     
         4 . The image inspection method according to  claim 3 ,
 wherein when the activity (Vn(t)) is second-order differentiated with respect to time (t) to obtain d 2 Vn(t)/dt 2 , if acceleration (d 2 Vn(t)/dt 2 )/Vn(t−1) is arranged in order of “positive, negative, and positive” or “negative, positive, and negative” along a time axis, a determination is made that an image disorder has occurred.   
     
     
         5 . The image inspection method according to  claim 1 ,
 wherein when the error is block noise, and if pixel values in an inspection block of the image signal is subjected to orthogonal transformation, and the transformation coefficient satisfies a predetermined condition, a determination is made that block noise has occurred.   
     
     
         6 . The image inspection method according to  claim 5 ,
 wherein when the transformation coefficient satisfies the predetermined condition, a determination is made that a corner has occurred in content displayed by the image signal.   
     
     
         7 . The image inspection method according to  claim 6 ,
 wherein the corner is distinguished between a corner due to block noise and a corner due to the content from the number of corners and a deviation thereof.   
     
     
         8 . A sound inspection method comprising:
 sampling a continuous digital sound signal by dividing the signal by less than or equal to 5 msec;   extracting a high-frequency component from the sampled signal; and   detecting an error occurred in a sound on the basis of the extracted high-frequency component.   
     
     
         9 . The sound inspection method according to  claim 8 ,
 wherein when the digital sound signal is recorded on a plurality of channels, detecting the error is carried out for each of the channels.   
     
     
         10 . The sound inspection method according to  claim 8 ,
 wherein when sampling is performed at time t along a time axis, frequency conversion is performed on the sampled signal, and n power values P n (t) and a total power value P(t) in a predetermined bandwidth are obtained, respectively,   [1] if the total power value P(t) is higher than a first threshold value, and   [2] if a value (P(t)/P(t−T)) produced by dividing the total power value P(t) by total power value P(t−T) at time (t−T) before that time, and a value (P(t)/P(t+T)) produced by dividing the total power value P(t) by total power values P(t+T) at time (t+T) after that time are individually higher than a second threshold value, and   [3] if values (P n (t)/P(T)) produced by dividing the individual power values P n (t) by the total power value P(T) are higher than a third threshold value, a determination is made that an error has occurred.   
     
     
         11 . The sound inspection method according to  claim 8 ,
 wherein when three power values along a time axis are compared, a first power value P n (t−T5) and a third power value P n (t+T+T5) are higher than a fourth threshold value, and a string of second power values P n (t), . . . , P n (t+T) is lower than a fifth threshold value, a determination is made that sound skipping has occurred.   
     
     
         12 . The sound inspection method according to  claim 8 ,
 wherein when three power values P n (t) along a time axis are compared, a first power value P n (t−T5) and a third power value P n (t+T+T5) are lower than a sixth threshold value, and a string of second power values P n (t), . . . , P n (t+T) is higher than a seventh threshold value, a determination is made that noise has occurred.   
     
     
         13 . The image inspection method according to  claim 2 ,
 wherein the error is an image disorder, and the extracted high-frequency component is an activity, the activity being an average of the variances of the digital image signal for each block.   
     
     
         14 . The image inspection method according to  claim 2 ,
 wherein when the error is block noise, and if pixel values in an inspection block of the image signal is subjected to orthogonal transformation, and the transformation coefficient satisfies a predetermined condition, a determination is made that block noise has occurred.   
     
     
         15 . The sound inspection method according to  claim 9 ,
 wherein when sampling is performed at time t along a time axis, frequency conversion is performed on the sampled signal, and n power values P n (t) and a total power value P(t) in a predetermined bandwidth are obtained, respectively,   [1] if the total power value P(t) is higher than a first threshold value, and   [2] if a value (P(t)/P(t−T)) produced by dividing the total power value P(t) by total power value P(t−T) at time (t−T) before that time, and a value (P(t)/P(t+T)) produced by dividing the total power value P(t) by total power values P(t+T) at time (t+T) after that time are individually higher than a second threshold value, and   [3] if values (P n (t)/P(T)) produced by dividing the individual power values P n (t) by the total power value P(T) are higher than a third threshold value, a determination is made that an error has occurred.   
     
     
         16 . The sound inspection method according to  claim 9 ,
 wherein when three power values along a time axis are compared, a first power value P n (t−T5) and a third power value P n (t+T+T5) are higher than a fourth threshold value, and a string of second power values P n (t), . . . , P n (t+T) is lower than a fifth threshold value, a determination is made that sound skipping has occurred.   
     
     
         17 . The sound inspection method according to  claim 9 ,
 wherein when three power values P n (t) along a time axis are compared, a first power value P n (t−T5) and a third power value P n (t+T+T5) are lower than a sixth threshold value, and a string of second power values P n (t), . . . , P n (t+T) is higher than a seventh threshold value, a determination is made that noise has occurred.   
     
     
         18 . The sound inspection method according to  claim 10 ,
 wherein when three power values along a time axis are compared, a first power value P n (t−T5) and a third power value P n (t+T+T5) are higher than a fourth threshold value, and a string of second power values P n (t), . . . , P n (t+T) is lower than a fifth threshold value, a determination is made that sound skipping has occurred.   
     
     
         19 . The sound inspection method according to  claim 10 ,
 wherein when three power values P n (t) along a time axis are compared, a first power value P n (t−T5) and a third power value P n (t+T+T5) are lower than a sixth threshold value, and a string of second power values P n (t), . . . , P n (t+T) is higher than a seventh threshold value, a determination is made that noise has occurred.